The present invention relates to printers and more particularly to printers which provide pre-collated duplex sheet output.
Printing is an important part of data processing systems for producing various reports and documents required for business. It is desirable that these reports or documents be printed on both sides of the page to produce a resultant savings in paper costs and a reduction in bulk of the individual report or document.
It has not been possible in the prior art to produce reports printed on both sides of the sheet (duplex printing) in a printer operating on-line with a data processing system. Recent advances in copier technology have made it easier and more economical to copy on both sides of the sheet. However, this represents a post-processing step for documents printed in a data processing system. One prime requirement for a duplex printer operating on-line with a data processing system is high throughout since the cost of processor time is relatively high and a printer which minimizes the processor time is to be desired. The copier systems are not suitable for incorporation into a printer since one of these systems duplexes only one sheet at a time which would be detrimental to printer throughput. A second system involves handling of printed sheets and/or originals from one position to another in the system which is detrimental to throughput and may also require operator attention.